Fresh El Cheapo "B" and "C" batteries for hollow state receivers

[k4kyv]

At the local Dollar General this morning I noticed that on the battery shelf, they have a made-in-China house brand 9V battery in a two-pack for $1.  That's 50˘ each.  Ten of these could be connected in series to form a 90V battery for $5.00, or a 45V battery for $2.50.  If you can find fresh old-buzzard-style radio batteries of that voltage range, they are MUCH more expensive.  The Chinese units are apparently non-alkaline, but even the zinc-carbon variety should give reasonable life - after all, that what the originals were.

Antique radio collectors could even take a crapped out Burgess, carefully open the cardboard case, remove the contents, and retrofit the seriesed 9v batteries inside to make it look original.

Not sure if these would work as bias packs for class-B or AB2  modulators, though, since the grid current in most class-B modulators is much higher than the battery drain on tube type receivers.  They should work OK for class AB1, however.

Does anyone know the maximum safe current drain rating for a standard 9V battery, before the ampere-hour (or better stated, milliamp-hour) rating is degraded?  They don't list this information anywhere on the battery case or package.

[Steve - WB3HUZ]

IIRC, typical alkaline 9V batts are good for something in the range of 500 mAH (at about a 10 mA load). Typical design loads will be on the order of 10-20 mA. Lithium types yield considerably more. Not sure of the max current rating.

[Vortex Joe - N3IBX]

Don,
     Many thanks for the post. I use these 9V batteries all the time for B+ supplies for old 1920's era TRF and regen sets. They work out FB. I just tap them off at 27V,45V and 90V. Some detectors like 27V, whilst others prefer 45VDC and 90V usually goes to the plates of the 01A's or 12A's in the last audio stage.

I use either a 6V wet cell for the A supply, or two 6VDC latern batteries in parallel to run all of teh filaments.

I've given serious consideration to using 9V batteries in series for bias packs. Why not?

Best Regards,
                  Joe N3IBX